Efficient development of a magnetic molecularly imprinted polymer for selective determination of trimethoprim and sulfamethoxazole in milk

A molecularly imprinted polymer was synthesized on the surface of magnetic nanoparticles for subsequent application in the extraction of trimethoprim (TMT) and sulfamethoxazole (SMX) residues in bovine milk. The magnetic polymer was suitably characterized and demonstrated high stability and optimum adsorption capacity under the conditions of analysis. MMIP was used in the preparation of milk samples by the magnetic solid phase extraction technique whose optimized parameters were: sample volume, elution solvent and its volume, amount of adsorbent, stirring time, and pH of the sample. The relative recoveries of analytes were 98.66 +/- 5.59% and 75.57 +/- 0.72% for TMT and SMX, respectively. The method developed was linear in the range of concentration of 0.05-20 mu g mL(-1) with correlation coefficients of 0.997 and 0.994 for TMT and SMX, respectively. It was also demonstrated satisfactory accuracy and precision, as well as adequate robustness and good drugs stability in the matrix. The method was applied satisfactorily in real milk samples contaminated with residues of these antibiotics.